Brush holder



June 1 3; 1944. woo Re. 22,496

BRUSH HOLDER Original Filed Nov. 23, 1942 Irwve ntor Alexander- P. Wood,

His Atto'r'neg.

Reissuecl June 13, 1944 UNITED STATES PATENT OFFICE BRUSH HOLDER.

Alexander P. Wood, Schenectady, N. Y., assignor to General ElectricCompany, a corporation of New York Original No.

Serial No.

ated February 8, 1944, 466,595, November 23, 1942. Application forreissue April 21, 1944, Serial No.

9 Claims. (Cl.

My invention relates to brush holders such as are used withdynamo-electric machines.

An object of my invention is to provide a shock-proof brush holderarranged to indicate the force exerted by this brush biasing device inbiasing a brush against a current collecting device of a machine inwhich the brush is employed.

Another object of my invention is to provide an improved brush holder inwhich a resilient retaining element is arranged to minimize accidentalchanging of the position of the pressure plate due to transient shocks.

Further objects and advantages of my invention will become apparent andmy invention will be better understood from the following descriptionreferring to the accompanying drawing, and the features of novelty whichcharacterize my invention will be pointed out with particularity in theclaims annexed to and forming part of this specification.

In the drawing, Fig. a brush holder embodying my 1 is a perspective viewof invention; Fig. 2 brush holder shown in Fig. l; and Fig. 3 is a planview of the brush holder shown in Figs. 1 and 2.

. In the accompanying drawing, I have shown an embodiment of myvinvention applied to a specific form of brush holder described andclaimed in Patent 1,693,319, Simmons, November 2'7, 1928, assigned tothe assignee of this application. It will be readily understood that theprinciple. of my invention is applicable to brush holders of anyconvenient form which can be used in connection with current collectingdevices, such as commutators and slip rings of dynamoelectric machines.

Referring to the drawing, I have shown an electrical contact brush |I|having a. conventional pigtail conductor lead H for connecting the brushin the circuit of the machine in which it is to be used. This brush inis arranged in contact with a current collecting slip ring device l2 andis supported byga brush holder having a brush guide member l3 forguiding the brush toward the slip ring. The brush holder is protendingguiding fingers I9 having fulcrum elements 2!) formed on the lower endsthereof adapted to extend into the stem guideway grooves Hi. The brushI0 is biased towards the slip ring l2 by a resilient compression coilspring 2| arranged about a spring seat formed by cylindrical flange 22on the lower side of the pressure plate I1 and a spring seat formed on apres sure tip element 23' in engagement with a contact clip 24 securedto the upper surface of the brush Ill. The compression spring 2|v biasesthe brush ll) away from the pressure plate l1 and also biases thepressure plate ll upwardly and tends to pivot it about the pressureplate fulcrums 20, such that the pressure plate locating edge I8 isresiliently biased into a stem slot l6 and the fulcrums 20 areresiliently biased against the sides of the guideway grooves I5 adjacentthe spring 2|. This produces a wedging action on the pressure plate I!which tends to retain it in position. It is desirable that the pressureon the brush Ill should be readily determinable without the use ofspecial force measuring devices, and this is readil determinable in theillustrated arrangement by the provision of a pressure indicating pin 25which is secured to the pressure tip 23 and extends parallel to thebrush I0 and through an opening formed through the pressure plate l1 andthe cylindrical flange 22. This pin 25 is formed with a plurality ofspaced apart graduation markings 2B which indicate the total pressure ofthe spring 2| on the brush HI. The springs 2| are formed to exert apredetermined pressure for a predetermined amount of compression, andthis compression is dependent upon the axial length of the spring 2|.For a given graduation mark 26 in registry with the top of the pressureplate IT, a predetermined pressure is exerted onthe brush ID by thespring 2|. Thus, the pressure plate l'l may be moved relative to thebrush into envided with an arrangement for biasing the brush against thecurrent collecting device which comprises a supporting stem l4 havinglongitudinally extending guideway grooves l5 in the sides thereof; and aplurality of slots l6 extending-transversely in one of the longitudinalfaces of, the stem l4 and arranged to cooperate with a pressure plate"having a locating edgelll adapted to fit into the stem slots l6.'Ihepressure plate 11 is provided with a pair'- or downwardly exgagementwith various slots l6 in the brush holder stem I4 to provide the desiredpressure on the brush It. Furthermore, as the brush ||l wears, itbecomes necessary to move the pressure plate ll somewhat nearer thebrush guiding member Hi to maintain substantially uniform pressure onthe brush throughout its useful life. It has been found that undercertain conditions of transient vibrations and shocks, there may be atemporary reduction in the biasingpressure of the spring 2| against thepressure plate H, or this pressure may be insuflicient to maintain thelocating edge 18 of the pressure plate H in position in the desired slotit of the brush holder stem [4, and the pressure plate I! may becomedislodged from its predetermined desired position, with the result thatthe pressure on the brush l may be st and poor contact result betweenthe brush l9 and the current collecting slip rin device I2. In order toprevent such dislodgment, a resilient coil retaining spring 21 isarranged with a loop of the spring in longitudinally slidable engagementwith the; back face of the brush holder stem [4, and the sides of thisspring extend around the stem M with inturned ends 28 thereof extendingthrough openings 29 formed in the guiding fingers l9v of the pressureplate I1, thereby securing the ends of the spring to the pressure plate.This spring.

retaining spring secured 10.

a plurality of slots extending transversely in said stem, a pressureplate adapted to fit into said stem slots, resilient means for biasing abrush through said guiding member and biasing said pressure plate intoone of said stem slots for holding said'pressure plate in -apredetermined position. .to provide substantially a predeterminedpressure on the brush, and means including a coil to said pressure plateand extending around said stem for resiliently holding said pressureplate in position in said stem groove to minimize dislodgement of saidpressure resiliently and firmly biases the locating edge l-B' j of thepressure plate I! into engagement with a slot l6 of the brush holderstem 14 and minimizes dislodgement of the pressure plate which mightresult from the transient conditions mentioned above without interferingwith the normal operation of the brush holder or the operation of thepressure adjusting feature thereof. Obviously; other types of biasingsprings might be used, and the spring shown in the drawing isillustrative of embodiment of this feature with the type brush holderillustrated. The brush holder is adapted to be secured toa supportingyoke or other suitable insulating frame or bushing by screws adapted toengage threaded openings 30 formed in the brush holder stem [4.

While I have illustrated and described a particular embodiment of myinvention, modifications thereof will occur to those skilled in the art.I desire it to invention is not to be limited to the particulararrangement disclosed, and I intend in the appended claims to cover allmodifications which do not depart from the spirit and scope of myinvention.

What I claim asnew and desire to Letters Patent of the United States,is:

1. A brush holder having a brush guiding member, a stem extending fromsaid guiding member, a plurality of slots extending transversely in saidstem, a pressure plate adapted to fit into said stem slots, resilientmeans for biasing a brush through said guiding member and biasing'saidpressure plate into one of said stem slots for holding" saidpredetermined position to pro vide a predetermined pressure on thebrush, and resilient means'connectedto said pressure plate and engagingsaid stem for resiliently holding said pressure plate in position insaid stem groove to secure by spring pressure on said 2. A brush holderhaving a brush guiding member, a stem extending from said guidingmember, a plurality of slots extending transversely in said stem, apressure-plate-adapted to fit into said stem vide substantially aposition against said stem to minimize dislodgement of said pressureplate due to "transient shocks-and reductions in biasing spring pressureon said pressure plate; i j 3. A brush holder having a brush guiding membe understood, therefore, that my ber, a stem extending from saidguiding member, 15

plate due totransient shocks and reductions in biasing spring. pressureon said pressure plate.

4.. A brush holder having a brush guiding member, a stem extending fromsaid guiding member, a guide way groove extending longitudinally in saidstem, a plurality of slots extending transversely in said stem, apressure plate adapted to fit into said stem slots and having a fulcrumelement adapted toextend into said stemguideway groove, resilient meansfor biasing a brush through said guiding member and biasing saidpressure plate into one of said stem slots and. said fulcrum elementagainst a side of said stem groove, and means secured tosaid pressureplate for resiliently holding said pressure plate in position in saidstem groove to minimize dislodgement of said pressure plate duetotransient shocks. and reductions in biasing spring pressure on. saidpressure plate.

5. A brush holder having a brush guiding. member, a stem extending-fromsaid: guiding member, a guideway groove extending longitudinally. insaid stem,- a plurality of slots extending transversely in said stem, apressure plate. having. a locating edgethereof adapted to fit into saidstem slots and having a guiding finger. provided: witlra fulcrum elementadapted to extend into. said stem guideway groove, resilient means forbiasing a brushthrough said guiding. member and biasing said pressureplate. locating edge into oneof said stem slots and said fulcrum elementagainsta side of said stemgroove for holding said pressure plate in apredetermined positionto provide substantially a predetermined pressureon the brush, and resilient means secured to said pressure. plate andextending around said stem fonresiliently sure plate due totransientshocks: and'reductions in biasing spring pressure on saidpressure plate.

6. A-brush holder having a brush guiding member, a stem extending fromsaid guidingmember, a guideway groove extending longitudinally in saidstem, a plurality of slots extending transversely in said stem,apressure plate havinga locating edge thereof adapted to fit into said:stem slots and having a guiding finger provided witha fulcrum elementadapted to extend into. said stem 7. A brush holder having a brushgrading memher, a stem extending from said guiding memher, a guidewaygroove extending longitudinally in said stem, a plurality of slotsextending transversely in said stem, a pressure plate having a locatingedge thereof adapted to fit into said stem slots and having a guidingfinger Provided with a fulcrum element adapted to extend into said stemguideway groove, res'lient means for biasing a brush through saidguiding member and biasing said pressure plate locating edge into one ofsaid stem slots and said fulcrum element against a side of said stemgroove for holding said pressure plate in a predetermined position toprovide substantially a predetermined pressure on the brush, and meansincluding a coil retaining spring secured to said pressure plate andextending around said stem for resiliently holding said pressur plate inposition against said stem to minimize dislodgement of said pressureplate due to transient shocks and reductions in biasing spring pressureon said pressure plate.

8. A brush holder having a brush guiding member, a stem extending fromsaid guiding member, a guideway groove extending longitudinally in saidstem, a plurality of slots extending transversely in said stem, apressure plate having a locating edge thereof adapted to fit into saidstem slots and having a guiding finger provided with a fulcrum elementadapted to extend into said stem guideway groove, resilient meansincluding a coil spring adapted to be compressed between said pressureplate and a brush in said guiding member for biasing the brush throughsaid guiding member and biasing said pressure plate locating edge intoone of said stem slots and said fulcrum element against a side of saidstem groove for holding said pressure plate in a predetermined positionto provide substantially a predetermined pressure on the brush, and

means including a coil retaining spring secured to said pressure plateand extending around said stem for resiliently holding said pressureplate in position against said stem to minimiz dislodgement of saidpressure plate due to transient shocks and reductions in biasing springpressure on said pressure plate.

9. A brush holder having a brush guiding member, a stem extending fromsaid guiding member, a plurality of slots extending transversely in saidstem, a pressure plate adapted to fit into said stem slots, resilientmeans for biasing a brush through said guiding member and biasing saidpressure plate into one of said stem slots for holding said pressureplate in a predetermined position to provide a predetermined pressure onthe brush, and resilient means arranged for engagement with saidpressure plate and for engagement with said stem for resiliently holdingsaid pressure plate in position in said stem groove to minimizedislodgement of said pressure plate due to transient shocks andreductions in biasing spring pressure on said pressure plate.

ALEXANDER P. WOOD.

